The truth of the matter is that the actual start of principal photography was never released. The Michigan Film Office originally stated that the filming would start sometime in the first quarter of 2014. Outlets like Screen Rant
ran with that and assumed that filming would be in February but no one actually really knew the date. The first quarter of 2014 runs from January to March, so the end of March could even be a possible date. Speaking of the Michigan Film Office, this week they reported
that although a date for the start and completion of filming in Metro Detroit and other areas haven't been confirmed yet, as spokesperson for the film office did say that filming will likely start this spring (which could be any time from March 20th to June 20th).